“Pasteur,” wrote M. Roux, “does not hesitate to declare that that microscopic organism is the most frequent cause of infection in recently delivered women. One day, in a discussion on puerperal fever at the Academy, one of his most weighty colleagues was eloquently enlarging upon the causes of epidemics in lying-in hospitals; Pasteur interrupted him from his place. ‘None of those things cause the epidemic; it is the nursing and medical staff who carry the microbe from an infected woman to a healthy one.’ And as the orator replied that he feared that microbe would never be found, Pasteur went to the blackboard and drew a diagram of the chain-like organism, saying: ‘There, that is what it is like!’ His conviction was so deep that he could not help expressing it forcibly. It would be impossible now to picture the state of surprise and stupefaction into which he would send the students and doctors in hospitals, when, with an assurance and simplicity almost disconcerting in a man who was entering a lying-in ward for the first time, he criticized the appliances, and declared that all the linen should be put into a sterilizing stove.” Pasteur was not satisfied with offering advice and criticism, making for himself irreconcilable enemies amongst those who were more desirous of personal distinction than of the progress of Science. In order the better to convince those who still doubted, he affirmed that, in a badly infected patient--what he usually and sorrowfully called an _invaded_ patient--he could bring the microbe into evidence by a simple pin prick on the finger tip of the unhappy woman doomed to die the next day. “And he did so,” writes M. Roux. “In spite of the tyranny of medical education which weighed down the public mind, some students were attracted, and came to the laboratory to examine more closely those matters, which allowed of such precise diagnosis and such confident prognosis.” What struggles, what efforts, were necessary before it could be instilled into every mind that a constant watch must be kept in the presence of those invisible foes, ready to invade the human body through the least scratch--that surgeons, dressers and nurses may become causes of infection and propagators of death through forgetfulness! and before the theory of germs and the all powerfulness of microbes could be put under a full light à propos of that discussion on puerperal fever! But Pasteur was supported and inspired during that period, perhaps the most fruitful of his existence, by the prescience that those notions meant the salvation of human lives, and that mothers need no longer be torn by death from the cradle of their new-born infants. “I shall force them to see; they will have to see!” he repeated with a holy wrath against doctors who continued to talk, from their study or at their clubs, with some scepticism, of those newly discovered little creatures, of those ultra-microscopic parasites, trying to moderate enthusiasm and even confidence.